Keeping a pilot or crew member at a comfortable temperature while in an aircraft cockpit is a well-known problem. Various thermal control systems have been developed addressing this problem. Of all such systems, the most typical is one that employs a closed loop liquid system for removing body heat combined with an open loop ambient air system that provides flight helmet or hood ventilation. Typically, the closed loop liquid system employs a dedicated freon vapor refrigeration unit and the open loop ambient air helmet ventilation system employs a dedicated blower.
A thermal control system which utilizes a dedicated freon vapor refrigeration unit has many significant drawbacks. The refrigeration unit has to be housed someplace aboard the aircraft. A pilot or crew member must, upon entering the aircraft cockpit, connect his body garment to the system. This requires at least two interfaces between the refrigeration unit and any one pilot or crew member; one interface being required for a liquid supply line to carry cooling fluid to the garment, and the other for removing warmed cooling fluid from the garment. Further, when the system also utilizes an ambient open loop air system for helmet ventilation and/or protection against chemical agents, an additional air supply line, filter and blower, and an associated interface is required for providing ambient air to the flight helmet.
A problem with each of the liquid line interfaces is that they require leak-proof quick connect/disconnect connectors between the garment and the refrigeration unit. This is important so that a pilot or crew member can easily enter or leave the cockpit without contaminating the cockpit with heat transfer fluid. Another problem is that a significant amount of maintenance is involved in making sure this type of system always has an adequate supply of heat transfer liquid and refrigerant, and in making sure that the refrigeration unit, which is a relatively complicated piece of machinery, is operating properly. Maintenance of this system may require special procedures, equipment and training, with regard to both the refrigeration unit and the garment itself.
Still another problem associated with the above system is that it imposes significant weight penalties on the particular aircraft in which it is used. The liquid in the system, the refrigeration unit, and the tubing required for transferring fluid between the garment and the refrigeration unit all add significant weight to the aircraft.
Still another drawback is that providing ambient air (filtered) to a flight helmet does not necessarily provide head cooling. Further, this type of system has been known to occupy significant volume in a cockpit and its use has resulted in significant cockpit noise.
The present invention has been developed for the purpose of solving the above-stated problems. Several U.S. patents are known to be pertinent to the patentability of the present invention. These patents are listed as follows: U.S. Pat. No. 2,557,099 issued to Green on June 19, 1951; U.S. Pat. No. 2,693,088 issued to Green on Nov. 2, 1954; U.S. Pat. No. 2,984,994 issued to Hankins on May 23, 1961; U.S. Pat. No. 3,000,616 issued to Spangler on Sept. 19, 1961; U.S. Pat. No. 3,474,790 issued to Benzinger on Oct. 28, 1969; U.S. Pat. No. 3,487,765 issued to Lang on Jan. 6, 1970; U.S. Pat. No. 3,500,827 issued to Paine on Mar. 17, 1970; U.S. Pat. No. 3,648,765 issued to Starr on Mar. 14, 1972; U.S. Pat. No. 3,736,764 issued to Chambers et al on June 5, 1973; U.S. Pat. No. 3,744,555 issued to Fletcher et al on July 10, 1973; U.S. Pat. No. 4,024,730 issued to Bell et al on May 24, 1977; U.S. Pat. No. 4,146,933 issued to Jenkins et al on Apr. 3, 1979; and U.S. Pat. No. 4,271,833 issued to Moretti on June 9, 1981.